Conventionally, various modified silicone compounds are known as silicones having hydrophilic groups and, conventionally polyether-modified silicones have been used as non-ionic silicones. Other than these, (poly)glycerin-modified silicones (Patent Documents 1 to 9), a sugar and polysaccharide-modified silicone compound (Patent Document 10), and the like have been proposed.
Polyether-modified silicones are ordinarily produced by adding a polyether having a reactive unsaturated group to an organohydrogensiloxane, and are beneficial in that these have a structural design with a high degree of freedom. For this reason, compatibility between a copolymer that is a reaction product and the unreacted polyether ordinarily included in the modified silicone is comparatively excellent and, therefore, in many cases, even when in a form of a mixture, polyether-modified silicones do not separate into two phases.
In contrast, silicones modified by polyglycerine, sugars, or polysaccharides have a low degree of freedom with respect to structural design, and this leads to the problem of the scope of use not being able to be expanded. Such polyhydric alcohol-modified silicones are ordinarily produced by adding a polyhydric alcohol derivative having a reactive unsaturated group to an organohydrogensiloxane. However, in many cases, compatibility between the remaining polyhydric alcohol derivative and the copolymer that is a reaction product is low, and such silicones separate into two phases within a short period of time following production.
Additionally, compatibility between organohydrogensiloxanes and such polyhydric alcohol derivatives is fundamentally low and, therefore, when the design is such that molecular weight of the copolymer exceeds about 5,000, the addition reaction does not complete even if a solvent is added, thus, in many cases, leading to difficulties in producing the target product. Even when the molecular weight is about 3,000, the unreacted product gradually separates or precipitates. This necessitates a task of removing the separated or precipitated material and is a large obstruction from the perspective of production efficiency as well. (Patent Documents 1, 6, 9, and 10)
Even when a compound is used in which a form of the hydroxyl group is protected as the polyhydric alcohol derivative, deprotection is required following completion of the reaction and, therefore, the problem of separation into two phases cannot be avoided. Additionally, heavy acidizing conditions must be introduced due to the deprotection in this method, and the desired product cannot be obtained in an easily reproducible manner as a result of disconnections of the silicone backbone occurring. (Patent Document 3)
Recently, Patent Document 8 has proposed a novel alternating copolymer of organopolysiloxane with polyglycerine derivative, and suggests that a high molecular weight polyglycerine-modified silicone can be obtained without the problem of white turbidness, and the like, caused by the unreacted raw material occurring. However, it is clear from the chemical structure that this compound has a hydrophilic group portion incorporated on its backbone. As a result, this copolymer has properties completely different that those of conventional general-use hydrophilic silicones such as polyether-modified silicone and the like and, therefore, a high level of technical skill is necessary to stably compound this copolymer in delicate formulations such as cosmetic products and the like, leading to the problem of the field of use being limited.
Patent Document 7 proposes a method for producing a branched polyglycerol-modified silicone obtained by adding/graft polymerizing a silicone having at least one functional group selected from the group consisting of hydroxy groups, carboxy groups, amino groups, imino groups, mercapto groups, and epoxy groups, with 2,3-epoxy-1-propanol in the presence of an acidic or basic catalyst. However, with this method, the siloxane backbone disconnects during the graft polymerization, which results in two or more components having different properties being prone to be produced as the copolymer. This leads to a multitude of problems related to product quality, refining processes, and the like.
For these reasons, there are few practical products among the conventional polyhydric alcohol-modified silicones, and, to-date, variation on chemical structure has been limited. Thus, there is a need for the development of a stable polyhydric alcohol-modified silicone that is easy to produce, and in which little separation into two phases and/or sedimentation or the like of the unreacted raw material occurs after production; and a method for producing said polyhydric alcohol-modified silicone.
Next, considering the interaction between various cosmetic raw materials and these silicones that have a hydrophilic group, it is understood first and foremost that various oil agents are compounded in cosmetic compositions and that each type of oil composition has strengths and weaknesses.
For example, silicone oils have strengths of a light feel and superior spreadability, superior water repellency, and a high degree of safety, but lack moisturizing feel. Moreover, problems exist such as that silicone oils with high volatility leave a dry feeling after application and silicone oils with low volatility impart an unnatural feeling of residue on the skin. In either case, it is difficult to attain a natural skin feel after application.
On the other hand, while ester oils have a problem in that they feel heavy and oily when applying, they have the strength of providing a natural skin feel after application. However, due to its high degree of oiliness, cosmetic compositions comprising ester oils have problems attaining moisturizing feel after application or, in other words, providing silky-smooth moisturization when applying and maintaining that feel thereafter.
Additionally, hydrocarbon oils have the strengths of being easily compounded in a cosmetic composition and spreading well, and hydrocarbon oils with high volatility provide a refreshing, light feel when applied. However, hydrocarbon oils are prone to break down sebum, causing the skin to whiten after application, which, in some cases, leads to a feeling of pulling or itchiness due to desiccation, and irritation. Hydrocarbon oils with low volatility have problems of feeling heavy when applying and feeling extremely oily.
In many cases, combinations of these oil agents are used in cosmetic composition formulations, whereby strengths thereof are promoted and weaknesses thereof are compensated for and, by further adding water, value as a cosmetic composition from the perspectives of skin care and the like due to feel and hydration increases. This is because oiliness is suppressed by the effects of water and, compared to cases where water is not added, and a clean skin feeling can easily be obtained.
Ordinarily, emulsification using a surfactant is performed in order to stably compound an oil agent and water in a cosmetic composition. From the perspectives of being difficult to obtain a stable emulsion using an organic surfactant and the sensation during use of the cosmetic composition being easily negatively affected when the oil agent system comprises a silicone oil, research into a silicone-based surfactant that is beneficial in terms of feel is actively being carried out.
Patent Documents 11 to 15 propose a method in which a polyoxyalkylene-modified organopolysiloxane (a polyether-modified silicone) having good compatibility with silicone oil is used as a surfactant for a water-in-oil emulsion. However, in some cases, emulsion stability of the polyether-modified silicone in mixed oil agent systems and the like is insufficient, and care is needed when formulating the cosmetic composition.
A method in which an organopolysiloxane (alkyl/polyether co-modified silicone) having both a long chain alkyl group and a polyoxyalkylene group is used as an emulsifier (see Patent Document 16), and a method in which a silicone branched polyether-modified silicone compound (e.g. an alkyl/linear siloxane branch/polyether co-modified silicone) is used as an emulsifier (see Patent Document 17) are proposed as methods to solve these problems.
Other examples of non-ionic silicone-based surfactants that have been proposed include various glycerin-modified silicones, and it is suggested that theses surfactants improve the squeaky feel and poor compatibility on the skin unique to silicone. Examples of the oil agent are recited in Patent Documents 18 and 19 and in Patent Documents 20 to 25, which are related to fluorine alkyl co-modification; examples of the surfactant are described in Patent Documents 1, 4, 5, and the like, in which glycerin-modified silicone compounds are recited; and examples of cosmetic compositions thereof are recited in Patent Documents 26 to 28. Recently, a silicone branched polyhydric alcohol-modified silicone (e.g. an alkyl/linear siloxane branch/polyglycerine co-modified silicone) has been proposed, and it is suggested that a cosmetic composition comprising this silicone has superior adhesion to the skin, is not sticky, has a clean feel after application, and has superior emulsion stability. (Patent Document 6)
All of these techniques take the approach of attempting to increase functionality as an oil or surfactant by introducing a modified group for the purpose of improving compatibility with the oil agent system in the structure of the silicone. Thus, the standpoint of taking advantage of the compounding effect of water described above is not prominent, and a cosmetic composition having excellent effects of providing the skin with silky-smooth moisture, and maintaining that feel thereafter has not been obtained. That is, the effect of suppressing the oiliness of conventional silicone-based surfactants is insufficient.
On the other hand, titanium oxide, zinc oxide, red iron oxide, and other exemplary pigments, and powders such as mica, sericite, and the like are widely used as basic cosmetic products, sunscreens, nail colors, nail coatings, foundations, mascaras, eye liners, and similar cosmetic compositions. However, with untreated powders, agglomeration due to electric charge or polarity of the powder surface, trace amounts of impurities, and the like occurs easily and, therefore, generally powders that have been surface treated with various treatment agents are used for the purpose enhancing the dispersibility and stability of the powder, and improving feel, water resistance, sebum resistance and the like when used in a cosmetic composition.
Known examples of such treatments include lipophilization treatments using an oil agent, a metal soap, or the like; hydrophilization treatments using a surfactant, water-soluble polymer, or the like; treatments using silicone compounds; silica treatments; alumina treatments; and the like. Particularly, in recent years, there have been many cases where treatment using a silicone compound having a reactive portion in the molecule have been performed. This is because of the following reasons. This treatment forms a chemical bond with the surface of the powder and, therefore, it is useful not only for improving the surface of the powder but, at the same time, also for sealing surface activity; treatment is carried out reliably; the treatment agent will not separate from the powder surface, even when used on a solvent-based cosmetic composition; and efficiency is good because changes in properties caused by treatment can be reduced.
For example, Patent Document 29 discloses a method of surface treating in which 12 to 60 parts by weight of methylhydrogenpolysiloxane are used per 100 parts by weight of a powder. However, in this method, unreacted Si—H groups still remain even after the treating of the surface of the powder and, therefore, there is a problem when this powder is compounded in a cosmetic composition because hydrogen gas is produced due to the liquid conditions of the powder.
Patent Document 30 proposes a method in which a polyether-modified silicone having an HLB value of greater than or equal to 2 and less than or equal to 7 is used as a dispersing aid for a powder. However, while this technique is effective when the oil agent is only a silicone system, in cases of a mixed oil agent system comprising an organic system, dispersion stability may be insufficient.
Patent Document 31 recites an improved powder treated using a polyglycerine-modified silicone. However, with this technology, dispersibility in oil agents is insufficient, the treated powder is prone to separation over time, and redispersibility is poor, which may lead to worsening of the quality and feel after application of the cosmetic composition.
Patent Document 32 describes a powder composition that is treated using a modified silicone that has an alcoholic OH group, and proposes an example of a triglycerin variant. However, in this case, there are the following problems. It is necessary to addition react a triglycerin derivative in which a hydroxyl group is protected by acetal with silicone and, thereafter, perform a reaction to remove the acetone. The production process is lengthened and reaction conditions of the deprotection group following the addition reaction are severe. The desired product cannot be obtained in an easily reproducible manner as a result of disconnections of the silicone backbone occurring.
Patent Document 33 recites a powder composition that is treated using a silicone branched polyglycerine-modified silicone (e.g. an alkyl/linear siloxane branch/polyglycerine co-modified silicone) and a powder in oil dispersion comprising the same. With this technology, when a method is used in which a powder is dispersed in the oil agent dispersing medium using the modified silicone, compared with the same method using the polyether-modified silicone described above, a stable powder in oil dispersion can be obtained. Additionally, dispersion stability in mixed oil agent systems is also improved. However, when using a method in which the powder composition, obtained by treating the powder surface using the modified silicone, is dispersed in the oil agent dispersing medium, the powder tends to easily agglomerate and/or precipitate.
Patent Document 34 recites a powder dispersion stabilizer comprising a two-end silicone modified glycerin and a powder dispersion composition in which the powder dispersion stabilizer is compounded. However, while this dispersion stabilizer displays superior effects when the oil agent is only a silicone system, there is a problem in that when the oil system is a mixed oil system comprising an organic system, the effects are insignificant.
In other words, with conventional technology related to powder dispersion and surface treatment, dispersion stability in mixed oil agent systems is insufficient. Additionally, from the perspective of providing a superior powder in oil dispersion with stability such that the powder does not agglomerate or precipitate after preparation of a powder composition obtained by treating a powder surface using a treatment agent, even in cases where a method is used in which the powder composition is dispersed in an oil agent dispersing medium, the degree of achievement of conventional technology is insufficient.
Furthermore, cosmetic compositions that have a small water content such as oil-based cosmetic compositions and the like generally have the following problems. 1) Easily produces discomfort related to such points as being extremely oily, being sticky or heavy, leaving a heavy coated feeling, and the like. 2) Moreover, lipsticks, eye shadows, eye liners, oil-based foundations, and similar oil-based makeup cosmetic compositions have poor cosmetic retainability after application to skin, and easily transfer or soak into clothing.
Compounding a silicone oil having superior spreadability, smoothness, and light feel is effective in mitigating the prominent oiliness of 1). However, when compounding a silicone oil, new problems arise such as an unnatural feeling on the skin unique to silicone oil, insufficient moisturizing feel, and the like. Moreover, there is a tendency for the feel of adherence to the skin, which is a characteristic of oil-based cosmetic compositions, to be inhibited.
Thus, from the perspective of improving the negative aspects of silicone oil as an oil agent, a cosmetic composition comprising a glycerin-modified silicone compound as an oil agent (Patent Document 18), an oil-based cosmetic composition comprising a polyglycerine-modified silicone compound having an alkyl group with 1 to 10 carbons as an oil agent component (Patent Document 19), an oil-based cosmetic composition comprising a polyglycerine-modified silicone compound including a long chain alkyl group having from 11 to 30 carbons (Patent Document 35), and similar development has been carried out.
On the other hand, with regards to the problem of cosmetic retainability described in 2), an oil-based solid cosmetic composition comprising one or at least two types of alkyl glyceryl ether-modified silicones (Patent Document 36), an oil-based cosmetic composition comprising a polyoxyalkylene-modified silicone and an alkyl glyceryl ether-modified silicone (Patent Document 37), Patent Document 38, and similar research has been performed. It is suggested that, after application, moisture is supplied into the applied layers of these oil-based cosmetic compositions from the skin, exhalation, or the like, and the viscosity of the alkyl glyceryl ether-modified silicone in the applied layer increases, leading to an increase in the viscosity of the applied layer and, thus, greater retainability of the cosmetic.
However, with these technologies, oiliness remains prominent and it has not been possible to obtain an oil-based cosmetic composition that can impart a natural feeling on the skin without discomfort and sufficient moisturizing feel after application (a cosmetic composition that is substantially water-free or has a small water content).
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Patent Document 2: Japanese Unexamined Patent Application Publication No. 5-62-195389 (Japanese Patent No. 2583412)
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Patent Document 12: Japanese Unexamined Patent Application Publication No. S-61-293904
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